Friction letoff



Aug. 9, 1949. F. s. LAKE EIAL mic'uon LETOFF Filed Oct. 4. 1946 4Sheets-Sheet 1 1 F. ammo LAKE JAMES WJRIMMEP- F. G..LAKE ET AL FRICTIONLETOFF Filed Oct. 4. 1946 4 Sheets-Sheet 2 I F. GERQRD LAKE JAM is W-TRIMMER a? .flllorng FRICTION LB'IOFP 4 Sheets-Sheet 3 Filed Oct. 4,1946 8. I. M on D I m +H 1 G H .r to o Y v on v on. u: 1 0- 3 wt to n vR 8 8 a u h M Q E mm m x. n UT a n w mu 3. N on m Jmas w. TRH'IMLI UMlib Aug. 9, 1949. LAKE ET AL FRICTION LETOFF 4 Sheet s Sheet 4 Filed Oct1 F. GERARD LAKE.

WWW M Patented Aug. 9, 1949 2,478,283 FRICTION LETOFF Francis GerardLake, New York, N. Y., and James W. Trimmer, Belmar, N. J., assignors toThe M. W. Kellogg Company, New York, N. Y., a

corporation of Delaware Application October 4, 1946, Serial No. 701,376

Claims.

The present invention relates generally to improvements in textile loomsand, as illustrated herein, relates more particularly to improvements inconstant tension friction let-ofis.

Positive let-offs of the Bartlett or the Roper types which employpositive actuating means actin through a braking member to cause thewarp I beam to rotate and thus pay off the warp are most commonly usedtoday in high speed looms. Such let-offs. however, are not entirelysatisfactory since they operate intermittently and hence permit periodicvariations in tension of the Warp threads. In many cases, such variationis objectionable since the Woven cloth will be streak or uneven whichresults in production of seconds with consequent loss to the textilemill operator.

Friction let-offs are more satisfactory from at least one aspect sincewarp is let-off uniformly and constantly. Friction let-offs, however,have not been satisfactory since they are affected by changes inatmospheric conditions. Friction between the friction surfaces variesaccording to temperature and humidity conditions and adjustments tocompensate for such change are not adequate to insure that constanttension will be maintained on the warp sheet. It has not been possible,as a practical matter, to provide fric--- tion let-oils with anysatisfactory means for compensating for the decrease in diameter of thewarp beam.

Present commercial 1etofis, either positive or friction type, aredifficult to service and maintain; and, since the repair or adjustmentof such let-offs involves the removal and replacement of many individualparts, the idle periods and loss of production of the machine due tosuch repairs or adjustments are excessive.

One object of the invention is to provide an improved friction let-offby the use of which the above-mentioned difficulties will be overcome.To this end and in accordance with one feature of the invention, thepresent friction let-off is provided with means for reducing the effectsof temperature and humidity on the friction surfaces thereof.

Another object of the invention is to provide improved means forcompensating for the decrease in diameter of the warp on the warp beam.To this end, means are provided for accurately varying the' pressurebetween the friction surfaces of the let-off.

A still further object of the invention is to provide an improvedfriction let-ofi which will maintain a constant tension on the warp bydeveloping a braking effect which, at any operating pressure between thefriction surfaces of the let-off, is predictable and substantiallyconstant. To accomplish this end, the novel friction let-off is soconstructed and arranged that in operation a relativel high rubbingvelocity is produced between the rotor and stator friction elementswhereby variations in said rubbing velocity do not result in large orunpredictable variations in braking effect.

A still further object of the invention is to provide a let-offmechanism which will reduce substantially the time necessary for repairand replacement thereof. To this end, the let-off mechanism is enclosedin a casing which permits the entire let-on mechanism to be removed as aunit.

A still further object of the invention is to improve generally upon theconstruction and operation of m let-offs.

With the above and other objects and features in view, the inventionwill now be described with particular reference to the accompanyingdravvings in which Fig. 1 is a view in side elevation of the portion ofthe left hand side of the loom to which the present let-off is applied.

Fig. 2 is an enlarged side elevation of the letoff of Fig. 1.

Fig. 3 is a sectional view taken along the line III-I11 of Fig. 2.

Fig. 4 is a sectional view taken along line IV--IV of Fig. 3; and

Fig. 5 is a sectional View taken along line V--V of Fig.3.

The present let-off illustrating a preferred embodiment of the inventionmay be applied to any present commercial type of loom havingconventional cast iron side frames if so desired, but is preferablyapplied to a loom having double web side frames. The drawings show onlya portion of a textile loom since a description of the remaining partsof the loom is not necessary for a complete understanding of the presentinvention.

The let-off mechanism, as shown most clearly in Fig. 1, is enclosed ina-casing it which is'inserted in an opening it in the outer web I 4 ofthe loom side frame iii. The opening I2 is surrounded by a pad 88,welded to the web It, which provides a-seat for the casing W. The framei6 is provided with an inner web l5 having an opening 20 arranged toreceive a boss 22 on the inner side of the casing ill and which acts toposition the casing ill, and the let-off mechanism contained therein, inproper operative relation t a gear 24 on the warp beam end 2%.

- the let-ofl mechanism.

Rotation of the shaft 34 and the warp beam is controlledby a frictionclutch or brake as will now be described. A spur gear 48 is locatedwithin the casing l8 and is keyed to the shaft 34. The gear 48 mesheswith a gear 42 fixed to a countershaft 44 which is rotatably mounted atone end in a bearing 46 supported in the body portion of the casing I8and at its other end in a bearing 48 in the cover 38. The shaft 44 haskeyed thereto a second spur gear 58 which meshes with a spur gear 52.

In order to obtain a sufllciently high rubbing velocity between therotor and the stator elements of the let-off mechanism and a smoothcontrol effect, the angular velocity of gear 24 is multiplied throughgears 36, 48, 42, 58 and 52. The

multiplication ratio chosen is best determined in each particular case.

The spur gear 52 is rotatable on the shaft 34. The spur gear 52 isprovided with a hub 54 which is recessed, as shown best in Fig. 3, toreceive bearings 58 on which the gear 52 rotates. The gear 48 and thegear 52 are spaced by a spacer 51 and the bearings 56 are maintained inpredetermined axial position by a spacer member 58 which is maintainedin position by a washer 68 and nuts 62 threaded on the end of the shaft34. The hub 54 of the gear 52 has welded thereto a disc 64 which isprovided with a circumferential recess 66. An annulus 68 of suitablefriction material is supported in the recess 66, as will later bedescribed.

The cover 38 of the casing I8 is provided with a cylindrical projectionI8 in which a sleeve I2 is mounted in alinement with the shaft 34 forangular and axial movement. This sleeve I2 at its outer end is providedwith a threaded opening I4 into which is threaded a thrust member I6which is arranged to move axially relatively the sleeve I2. The thrustmember I6 at its inner end is provided with a bore for receiving the endof the shaft 34 so that the inner enlarged end I8 thereof projectsbeyond the end of the spacing sleeve 58. The end I8 carries a disc 88which is provided with a shouldered circumferential portion 82 forreceiving a ring 84. The ring 84 is maintained in position on the disc88 by means of spaced shouldered bolts 86. The ring 84 is provided witha plurality of spaced notches 88 for receiving rods 98 which aremaintained in position within the casing I8 by cap screws 92 extendingthrough inwardly extending brackets 94 formed as a part of the casing I8and supporting the rods 98. Thus, the ring 84 ismovable axially but isheld from rotation. The thrust member I6 and the sleeve I2 are mountedfor limited rotation relatively to the ring 84 as will later becomeapparent.

The ring 84 has fixed thereto a plurality of members 96, each having acircular projection thereon for receiving one end of a compressionspring 98. The other end of each of said springs 98 is received in asimilar circular projection I88 fixed to annulus I 82. The annulus I 82is substantially identical with the ring 84 and is provided withrecesses I8I for receiving the rods 98. Thus, rotation of the annulusI82 is prevented 4 although it may move axially relatively to the rods98. The friction ring 68 is maintained in position between the disc 84and the annulus I82 by pressure exerted by the springs 88. The springs88 are maintained under slight initial pressure at all times by thethrust member I6.

' Theconstruction, thus. far described, provides simple and effectivemeans for braking the rotation of the warp beam. In operation, when thetension on the warp sheet tends to exceed a pre-v determined value, thatis, the value for which the braking pressure between annulus I82, thefriction annulus 68 and the disc 64 is set, the warp beam and gearsofthe let-off meshing therewith will tend torotate at an increased rateto prevent the tension of the warp sheet from substantially exceedingthe predetermined value.

The diameter of the warp on the warp beam constantly decreases duringoperation of the loom and, consequently, means must be provided tocompensate for this decrease in diameter in order to maintain constanttension on the warp sheet. To this end, the present construction isprovided with means controlled by the diameter of the warpon the warpbeam.

I The initial pressure of the compression springs g 88 is controlled bythe thrust member I8 which is rotated in the threaded opening 14 to varythe axial position thereof. The sleeve 12, in which the thrust member I6is mounted, is prevented from moving axially by a plug I84 which extendsthrough a selected one of a plurality of openings in the projection 18and into cam grooves I86. Thus, turning of the thrust member I6 in onedirection will cause the member I6 to move axially to the friction ring68, the thrust member I2 is locked in position by tightening a lock nutI88.

In order to vary the frictional drag on the warp beam as the diameter ofthe warp thereon decreases, means is provided for rotating the sleeve72. The pin or plug I 84, as above stated, is located in the selectedone of the cam grooves I86 and rotation of the sleeve 12 in a clockwisedirection, as viewed in Fig. 1 will cause outward axial movement of thesleeve 12 with consequent de- 6 crease of tension on the springs 98. Thesleeve 72 is provided with gear teeth II8 meshing into a gear segmentII2 fixed to a horizontal shaft II4 mounted in bearings H6 and H8 in thecasing cover 38 and the body portion 28 of the casing I8,

respectively. The shaft II4 extends inwardly of the loom frame and atits inner end has fixed thereto a vertically extending arm I28 which isarranged to bear against the yarn on the warp beam and is maintained incontact therewith by a tension spring I22. Thus as the diameter of thewarp decreases, the arm I28 will swing in a counterclockwise directionand, through the segment II2, will cause rotation of the sleeve I8 in aclockwise direction. The shape of each cam groove I86 is carefullycalculated to insure that the warp sheet will be maintained underconstant tension until warp on the warp beam is exhausted. A pluralityof cam grooves I86 are provided for different yarn and weaving condi- 7tions.

It is to be noted that the casing and cover are I oil-tight. Theopenings in the cover and easing are all provided with oil seals I26 toprevent leakage of oil contained within the casing. All of the partsrotate in an oil bath which not only provides adequate lubrication butprovides means for preventing atmospheric moisture from affecting thefriction elements of the let-off. Since the operating parts are enclosedin a sealed casing, dirt and lint cannot enter to affect the operationthereof. The cover 30 and the body portion 28 of the casing are securedtogether in oil tight relation by cap-screws lit and the entireconstruction is inserted in the opening it and secured in position bymeans of cap-screws i311.

In order to obtain the best results with the letofi just described, theratios between gears 2t and ft, gears til and t2 and gears 56 and 52 areso chosen that in operation disc M rotates relative to friction annulust8 and annulus m2 at such a speed that the relative rubbing velocity issuch as to insure operation in a region of hydrodynamic lubrication.Preferably, said rubbing velocity should be in that region of thefriction-rubbing velocity curve beyond the minimum value between staticand kinetic friction. The jnetals used for the disc M and annulus tilt,the material used for the friction annulus til, the surface areas of thedisc til and annulus lti and friction annulus t3, and the lubricantemployed are all factors in-- volved in obtaining the desired frictionaloperation. if proper consideration is given to these factors and asuitable operating speed of disctd is chosen so that normal operation isin the region of kinetic friction, adjacent to or beyond the minimumvalue between static and kinetic friction, referring to thefriction-rubbing velocity curve, then the increases or decreases in theangular velocity of disc t l, necessary to maintain the predeterminedtension on the warp sheet will resuit in only small increase or decreasein the friction developed and the braking effect will be predictable andsubstantially constant.

The let-off described above effectively maintains the warp sheet undersubstantially constant tension regardless of the diameter of the warp onthe warp beam and permits the warp to be letoff continuously anduniformly as the weaving operation continues. Varying temperature andhumidity conditions have little if any effect on the tension of thewarp.

Having thus described our invention, what we claim. as new and desire tosecure by Letters Patent of the United States is:

i. in a loom, a rotatable warp beam having warp wound thereon, a gear onsaid warp beam, at speed multiplying gear train connected to said warpbeam gear, a friction element rotatable by said gear train, a secondfriction element restrained from rotation and frictionally engaging saidrotatable friction element, spring means for maintaining said frictionmeans in pressure engagement, means for adjusting the initial pressureof said spring means, a rotatable and axially movable member'for varyingsaid spring pressure, and means controlled by the diameter of the Warpon the warp beam for rotating said axially movable member and causingaxial movement thereof to decrease the spring pressure to maintain thewarp under constant and uniform tension as the diameter of the warp beamdecreases.

2. In a loom, a rotatable warp beam having warp wound thereon, arotatable friction element, a speed increasing gear train operativelyconnecting said warp beam to said friction element for causing saidfriction element to rotate at a high angular velocity as compared tosaid warp beam, a friction element movable axially into pressureengagement with said rotatable friction element. spring means forpressing said friction elements into engagement, means for applyinginitial pressure to said spring means, a rotatable and axially movablecam member for varying said spring pressure, and means controlled by thediameter of the warp on the warp beam for rotating said cam member andcausing axial movement thereof in a direction to decrease the springpressure on said friction element as the diameter of the warp on thewarp beam'decreases.

3. In a loom, a rotatable warp beam having warp wound thereon, arotatable friction element, a speed increasing gear train operativelyconnecting said warp beam to said friction element for causing saidfriction element to rotate at a high angular velocity as compared tosaid warp beam, a friction element movable axially into pressureengagement with said rotatable friction element,

' spring means for pressing sgid friction elements into engagement,means or tensioning said springs to apply an initial predeterminedpressure to said friction elements, a rotatable axially movable cammember for varying said pressure, and means controlled by the diameterof the warp on the warp beam for rotating said cam member and causingaxial movement thereof in a direction to decrease said pressure as thediameter of the warp on said warp beam decreases.

4. A loom let-off comprising means for multiplying the rotative movementof a warp beam,

1 and means for continuously restraining said r0- tative movement tomaintain a predetermined tension on the warp, said restraining meansincluding juxtaposed relatively rotatable elements having surfaces inslide engagement and means for lubricating said surfaces, saidmultiplying means having its input end connected to the warp beam andits output end connected to one of said relatively rotatable elements.

5. A loom let-off comprising means for multiplying the rotative movementof a warp beam, and means for continuously restraining said rotativemovement to maintain a predetermined tension on the warp, saidrestraining means including juxtaposed relatively rotatable elementshaving surfaces in slide engagement and a body of lubricating oil intowhich said members extend, said multiplying means having its input endconnected to the warp beam and its output beam connected to one of saidrelatively rotatable elements.

6. A loom let-off comprising a multiplying gear train, having its inputgear operatively connected to a warp beam, a device adapted tocontinuously impose a brake-effect on said warp beam through said geartrain, said device including an element mounted for rotation andoperatively connected to the output gear of said gear train, an elementmounted proximate said rotatable element and held against rotationrelative thereto, said elements having juxtaposed surfaces in slideengagement, means for applying pressure to said elements, and a body ofoil into which said elements extend for lubricating said juxtaposedsurfaces, the friction developed by said elements being in the region ofkinetic friction whereby as the rotation of the warp beam approacheszero during the weaving cycle the said developed friction does notincrease markedly and said gear train and rotatable element continuemovement due to their inertia and carry the beam through the zero pointof its movement in said cycle.

7. A loom let-off comprising a device adapted to impose a brake-effecton the rotation of a warp beam, said device including an element mountedfor rotation, a second element proximate said rotatable element and heldagainst rotation relative thereto, said elements having juxtaposedsurfaces in sliding engagement, means for applying pressure to saidelements, and a body of oil into which said elements extend forlubricating said juxtaposed surfaces, and a gear train having its inputgear operatively connected to the warp beam and its output gearoperatively connected to said rotatable element, the multiplying ratioof said gear train, the characterof said surfaces and the lubricatingqualities of said oil body being such that the rubbing frictiondeveloped by said juxtaposed surfaces is substantially continuously inthe hydrodynamic range,

8. A loom let-ofi comprising a device adapted to impose a brake-effecton the rotation of a warp beam, said device including an element mountedproximate said first element and held against rotation relative thereto,said elements having juxtaposed surfaces in slide engagement, means forapplying pressure to said elements, and a body of oil into which saidelements extend for lubrieating said juxtaposed surfaces, a multiplyinggear train having its input gear operatively connected to the warp beam,and its output gear operatively connected to said rotatable element, themultiplying ratio of said gear train, the character of said surfaces andthe lubricating qualities of said oil body being such that the rubbingvelocity of said elements is constantly in that region of the frictionrubbing velocity curve beyond the minimum value between static andkinetic friction.

9. A loom let-off comprising a friction device including a rotatablefriction member, a relatively stationary friction member, means forapplying pressure to said friction members, and means for lubricatingthe surfaces of said friction members, means operatively connected tothe warp beam and the rotatable friction member for rotating saidfriction member, and means controlled by the diameter of the warp on thewarp beam and operatively connected to said pressure applying means forvarying the pressure on said I friction members to permit yarn to bepayed ofi the warp beam at substantially constant tension as thediameter of the warp on the warp beam varies.

10. A loom let-ofi comprising means for multilying the rotative movementof a warp beam and having its input end connected to said warp beam,means continuously imposing a brake-effect on the rotation of the warpbeam through said multiplying means, said brake-effect imposing meansincluding a stationary element and a rotary element connected to theoutput end of said multiplying means and having juxtaposed surfaces inslide engagement, adjustable means for applying pressure to saidelements, and a body of lubricating oil into which said elements extendto lubricate said surfaces, and means controlled by the diameter of thewarp on the warp beam and operatively connected to said adjustable meansto reduce the pressure applied to said elements as said diameterreduces, whereby the friction developed by said elements varies withvariations in the speed of rotation of said rotary element substantiallyas a straight line function of gentle slope and the brake-effect imposedreduced from full beam to empty beam substantially as a straight linefunction.

FRANCIS GERARD LAKE. JAMES W. TRIMTMER.

REFERENCES CK'EED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 43,338 Reynolds June 28, 1864376,353 Thompson Jan. 10, 1388 1,421,241 Ingham June 27, 1922 1,741,300Holmes Dec. 31, 1929 1,759,531 Wells May 20, 1930 2,007,023 Payne July2, 1935 2,103,821 Payne Dec. 28, 1937 2,246,657 Bahan June 24, 1941

